1. Field of the Invention
The present invention generally relates to semiconductor power devices and more particularly to a semiconductor power device having a stacked discrete inductor structure wherein at least one semiconductor component is stacked on, and electrically coupled to electrodes of, a discrete inductor. Routing connections formed on the discrete inductor provide additional contacts to the at least one semiconductor component.
2. Description of Related Art
It is well known to include a discrete inductor on the printed circuit board when implementing a power converter circuit. For example, the Analogic™TECH 1 MHz 400 mA Step-Down Converter (AAT1143) requires the use of a discrete inductor. Power converters implemented in this way suffer the disadvantages of having higher component cost and of requiring more printed circuit board space.
Discrete inductors co-packaged with power ICs and other components are also well known. For example, the LTM®4600 DC/DC power converter available from Linear Technology Corporation of Milpitas, Calif., includes a built-in inductor in a 15 mm×15 mm×2.8 mm package. The package disadvantageously uses valuable printed circuit board space.
It is further known to dispose an inductor on top of an integrated circuit die such as a power converter integrated circuit die. For example, power converters available from Enpirion of Bridgewater, N.J., include a MEMS-based inductor having a thick electroplated copper spiral coil sandwiched between two planar magnetic layers and disposed over an integrated DC-DC converter. To achieve high inductance, a large die (sometimes referred to as the Power-IC die) is required in order to support a relatively large MEMS inductor substrate and achieve the desired electrical characteristics (high inductance and low resistance). This results in a higher product cost since the cost of the Power-IC, on a per unit area basis, is much higher than that of the inductor. This also results in a large overall package size. Furthermore, complex processing is necessary in order to fabricate the planar magnetic layers and the overall inductor structure having appropriate electrical characteristics.
Chip scale processing techniques have been used to combine a power IC and an inductor in a single package. An inductor substrate forms the bulk of the chip scale package that includes an optimized planar spiral inductor as disclosed in commonly assigned U.S. patent application Ser. No. 11/729,311, filed on Mar. 27, 2007, and entitled “Chip Scale Power Converter Package Having an Inductor Substrate”. A power IC is flipped onto the inductor substrate to form the chip scale power converter.
There remains a need in the art for a semiconductor power device requiring an inductor that achieves improved cost performance. The semiconductor power device preferably finds use in any application requiring an inductor. The semiconductor device also preferably finds use in power conversion applications such as buck, boost, and buck-boost converters and power regulation. The semiconductor power device further preferably uses existing high performance discrete power inductors co-packaged with a semiconductor component such as a power management IC and other discrete components such as field effect transistors and diodes. The semiconductor power device is preferably cost effective and has a small form factor.